CVE-2021-31553

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    CVE-2021-31553

    Published: 22 Apr 2021Last Modified: 9 Jul 2026

    Summary:

    Details: An issue was discovered in the CheckUser extension for MediaWiki through 1.35.2. MediaWiki usernames with trailing whitespace could be stored in the cu_log database table such that denial of service occurred for certain CheckUser extension pages and functionality. For example, the attacker could turn off Special:CheckUserLog and thus interfere with usage tracking.

    References: https://phabricator.wikimedia.org/T275669, https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666963, https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666964, https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667023, https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667024, https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667025, https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667027

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -None

    Affected versions

    1.35.2
    1.35.1
    1.35.0
    1.35.0-rc.3
    1.35.0-rc.2
    1.35.0-rc.1
    1.35.0-rc.0

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2021-31553 | CVE-DB